Seegrotte: Europe's Largest Underground Lake

The Seegrotte in Hinterbrühl, Lower Austria, offers a unique subterranean adventure. Originally a gypsum mine dating back to the 19th century, disaster struck in 1912 when an explosion flooded the lower caverns, creating what is believed to be Europe's largest underground lake. Rediscovered in the 1930s, it was transformed into a show mine, captivating visitors with its eerie beauty and fascinating history. The tour begins with a guided walk through the old mine tunnels, where you'll learn about the site's geology and mining past. Descend into the depths and witness the emerald-green waters of the 6,200 square meter lake. The highlight is a boat trip across the lake, gliding through the illuminated grotto. During World War II, the Nazis utilized the Seegrotte as a secret underground aircraft factory, forcing laborers to produce parts for the Heinkel He 162 jet fighter. An exhibit within the grotto sheds light on this dark chapter of history, serving as a reminder of the atrocities committed during the war. A monument above the lake commemorates the 51 prisoners who perished during a forced march to Mauthausen. Visitors can also see the miners' chapel, dedicated to St. Barbara, the patron saint of miners, completed in 1864. The altar features the initials "GA" (Glück Auf), a traditional miners' greeting. The Seegrotte's constant temperature of 9°C (48°F) makes it a cool escape, so wearing warm clothing and sturdy shoes is recommended.